The present invention relates to a bulk polymerization and esterification process for maximizing the conversion of an aliphatic alkanol to an ester in a radically-initiated polymerization of an ethylenically unsaturated acid-functional monomer, to the polymeric products produced by the process, to polymeric products, to processes for preparing emulsions and dispersions utilizing the polymeric products, and to overprint varnishes (OPVs), inks, coatings, surfactants, adhesives, paints, primers, and floor polishes containing the polymeric products.
Conventional solvent-based industrial finishes and coatings have presented many problems to date. Organic solvents can pollute the workplace and environment. In addition, many organic solvents are readily ignited, toxic, expensive, and lower the quality of finishes, and they can add undesirable colors to an otherwise colorless finish. As a replacement for these solvent-based finishes, the trend in the polymer industry has been toward high solids, liquid coatings and polymerization processes reducing or eliminating solvent.
High solids coatings offer significant advantages over conventional, solvent-thinned coatings. For example, high solids coatings do not pollute the air, they reduce or eliminate exudation of fumes in use, they reduce the energy requirements for their preparation in terms of material, energy expended and labor, and unlike solvent-based systems, they do not present significant fire and toxicity problems. High solids coatings also provide substantial advantages over other high solids liquids, such as solventless, water-borne, powder and non-aqueous systems. Additionally, they offer a better balance of properties.
One of the most enduring and difficult problems in preparing and utilizing high solids coatings is the selection and control of viscosity. Significant efforts have been made to improve processes and polymeric products for use in high solids applications. For example, various methods of characterizing polymers such as the number average molecular weight (Mn), weight average molecular weight (Mw), and the sedimentation average molecular weight (Mz) and ratios calculated using these characteristics such as the polydispersity ratio (Mw/Mn) and the dispersion index (Mz/Mn) have been investigated and adjusted to obtain polymeric products with viscosities useful for high solids applications. Although these efforts have produced vast improvements in polymers for use in high solids applications, improved processes are required to produce polymers with characteristics maximized for high solids applications.
U.S. Pat. No. 4,414,370 discloses a continuous bulk polymerization process for polymerizing vinylic monomers to prepare low molecular weight polymers employing thermal initiation at reaction temperatures from 235xc2x0 C. to 310xc2x0 C. and residence times of at least 2 minutes in a continuous stirred reactor zone. The vinylic monomers of the disclosed process include styrenic monomers such as styrene and xcex1-methylstyrene; acrylic monomers such as acrylic acid, methacrylic acid, acrylates, methacrylates; and other non-acrylic ethylenic monomers such as vinyl acetate.
U.S. Pat. No. 4,529,787 discloses a continuous bulk polymerization process including an initiator for preparing low molecular weight, uniform polymers from vinylic monomers at short residence times and moderate reaction temperatures to provide high yields of a product suitable for high solids applications. The disclosed vinyl monomers include styrenic monomers such as styrene and xcex1-methylstyrene; acrylic monomers such as acrylic acid, methacrylic acid, acrylates, methacrylates, and functional acrylic monomers; and non-acrylic ethylenic monomers such as maleic anhydride and vinyl pyrrolidone.
U.S. Pat. No. 4,546,160 discloses a continuous bulk polymerization process for polymerizing acrylic monomers to prepare low molecular weight, uniform, polymers for use in high solids applications which uses a minor amount of initiator at short residence times and moderate temperatures.
U.S. Pat. No. 5,130,369 discloses a batch process for preparing functionalized polymeric compositions. The functionalized polymeric compositions are prepared by polymerizing an ethylenically unsaturated functional monomer in a solvent including a reactive compound. The polymeric compositions prepared according to the process can be used as builders in detergent compositions, as pigments, dispersants in coating compositions, as tanning agents for leather, as associative thickeners and as rheology modifiers in coating compositions.
U.S. Pat. No. 5,521,267 discloses a batch process for preparing polymers from ethylenically unsaturated compounds containing acid groups with further ethylenically unsaturated compounds and monohydroxy compounds The polymer industry has long known that continuous polymerization processes are best for obtaining large quantities of polymeric product. Furthermore, optimized continuous processes provide economic advantages over batch polymerization processes and may provide more uniform polymeric products. While continuous processes have been disclosed for the preparation of certain polymeric products for use in high solids coatings applications, a continuous process is needed for preparing polymeric products with improved viscosity characteristics in aqueous media for use in high solids applications. Furthermore, a need remains for a polymerization process which incorporates an esterification reaction in which an alcohol with desirable viscosity-modifying behavior is incorporated into a polymeric chain with a high degree of conversion.
It would be highly desirable to be able to produce a polymeric product exhibiting low viscosity in aqueous solution using a continuous polymerization process where an alkanol is incorporated with high conversion into the polymer via an esterification reaction with an ethylenically unsaturated acid-functional monomer or a residue of such a monomer already present in the polymer.
One object of the invention is to provide a continuous bulk polymerization and esterification process including charging continuously into a reaction zone at least one ethylenically unsaturated acid-functional monomer and at least one alkanol having the formula ROH, where R is a linear or branched chain alkyl moiety, or combinations thereof, having greater than 11 carbon atoms. The process also includes maintaining a flow rate through the reaction zone sufficient to provide an average residence time of the monomers in the reaction zone of less than 60 minutes and maintaining a temperature in the reaction zone sufficient to produce a polymeric product. Preferably, the polymeric product of the continuous bulk polymerization and esterification process incorporates at least 80 percent of the alkanol as an ester of the ethylenically unsaturated acid-functional monomer when the alkanol is present in the reaction zone in an average amount of at least up to 25 mole percent of the total moles of the ethylenically unsaturated monomers. More preferably, the polymeric product of the continuous bulk polymerization and esterification process incorporates at least 85 percent of the alkanol as an ester of the ethylenically unsaturated acid-functional monomer when the alkanol is present in the reaction zone in an average amount of at least up to 20 mole percent of the total moles of the ethylenically unsaturated monomers. Most preferably, the polymeric product of the continuous bulk polymerization and esterification process incorporates at least 90 percent of the alkanol as an ester of the ethylenically unsaturated acid-functional monomer when the alkanol is present in the reaction zone in an average amount of at least up to 15 mole percent of the total moles of the ethylenically unsaturated monomers.
In preferred processes, the ethylenically unsaturated acid-functional monomer is acrylic acid, methacrylic acid, or crotonic acid while in other preferred processes, the R group of the alkanol has 12 to 50 carbon atoms and all combinations and subcombinations and ranges contained therein. More preferably, the R group of the alkanol has 12 to 36 carbon atoms, or 12 to 22 carbon atoms. In especially preferred processes, the alkanol has 16 to 18 carbon atoms, and in other especially preferred processes a mixture of alkanols, particularly those having 16 to 18 carbon atoms is used. In some preferred processes and products, the polymeric product has an aqueous solution viscosity which is less than about 50 percent of the aqueous solution viscosity of the equivalent unmodified polymeric product.
In still other preferred processes, the polymeric product has an acid number ranging from about 10 to about 740.
Other preferred processes further include adding a polymerization initiator, preferably di-t-butyl peroxide, into the reaction zone, preferably in an amount to provide a molar ratio of the initiator to the combined monomers of from about 0.0005:1 to 0.04:1. In other preferred processes, the polymerization and esterification process incorporates at least 95 percent of the alkanol as an ester of the polymerized ethylenically unsaturated acid-functional monomer when the alkanol is present in the reaction zone in an average amount of at least up to 15 mole percent of the total moles of the ethylenically unsaturated acid-functional monomers.
In preferred processes, the average residence time in the reaction zone is less than 30 minutes while in other preferred processes the temperature in the reaction zone ranges from 180 to 270xc2x0 C.
Preferred processes include continuously charging into the reaction zone at least one aromatic ethylenically unsaturated monomer, a C1 to C8 alkyl acrylate monomer, a C1 to C8 alkyl methacrylate monomer, or a non-aromatic ethylenically unsaturated vinyl monomer, while in other preferred processes at least two different aromatic ethylenically unsaturated monomers are continuously charged into the reaction zone.
In still another preferred process, at least two different alkanols are continuously charged into the reaction zone.
Another object of the present invention is to provide a continuous bulk polymerization and esterification process including continuously charging into a reaction zone at least one ethylenically unsaturated acid-functional monomer and at least one alkanol having the formula ROH, where R is a linear or branched chain alkyl moiety having from 12 to 50 carbon atoms and all combinations and subcombinations and ranges contained therein. The process also includes maintaining a flow rate through the reaction zone sufficient to provide an average residence time in the reaction zone of less than 60 minutes and maintaining a temperature in the reaction zone sufficient to produce a polymeric product. The polymeric product of the continuous bulk polymerization and esterification process has a number average molecular weight ranging from 600 to 20,000. Furthermore, an aqueous resin cut of the polymeric product has a solution viscosity which is less than about 50 percent of the solution viscosity of the equivalent unmodified polymeric product.
Another object of the invention is to provide a polymeric product consisting essentially of about 3 to about 97 percent by weight of a residue of at least one ethylenically unsaturated acid-functional monomer; about 3 to about 97 percent by weight at least one ester of the ethylenically unsaturated acid-functional monomers having an xe2x80x94OR group, where R is a linear or branched chain alkyl moiety having greater than 11 carbon atoms; about 0 to about 85 percent by weight of a residue of at least one aromatic ethylenically unsaturated monomer; and about 0 to about 85 percent by weight of a residue of at least one non-aromatic ethylenically unsaturated vinyl monomer.
A further object of the invention is to provide water-based compositions including water; from about 0.1 to about 100 percent by weight based on the total weight of the composition of the polymeric product of the invention or the polymeric product produced by the continuous bulk polymerization and esterification process; and up to about 99 percent by weight based on the total weight of the composition of an adjunct.
Preferred water-based compositions contain about 10 to about 99 percent by weight of the adjunct while other preferred water-based compositions are overprint varnishes, inks, coating materials, adhesives, floor polishes, paints, primers, and paper sizing agents.
A further object of the invention is to provide a process for preparing an emulsion of a polyolefin resin which includes mixing together a polyolefin resin and the polymeric product of the bulk polymerization and esterification process; mixing a base with the combination; and mixing the combined base, resin and polymeric product with water.
Another object of the invention is to provide the emulsion prepared by the above emulsion preparation process.
Still another object of the invention is to provide an emulsion of a polyolefin resin which includes a polyolefin resin, the polymeric product of the invention, a base, and water. In preferred processes and compositions containing a polyolefin resin, the polyolefin resin has a number average molecular weight ranging from about 500 to about 20,000, an acid number of about 0 to about 150, or a melting point of about 40xc2x0 to about 250xc2x0 C.
Yet another object of the invention is to provide a process for preparing a wax dispersion which includes mixing a wax in an aqueous medium with the polymeric product of the continuous bulk polymerization and esterification process.
Yet another object of the invention is to provide a wax dispersion prepared according to the above process for preparing a wax dispersion.
Yet another object of the invention is to provide a wax dispersion which includes a wax; the polymeric product of the invention; and an aqueous medium.
A still further object of the invention is to provide a process for preparing an oil emulsion which includes heating a mixture of an oil and the polymeric product of the continuous bulk polymerization and esterification process; mixing a base with the heated mixture of the oil and the polymeric product; and mixing water with the combined components.
Still another object of the invention is to provide an oil emulsion prepared according to the above process for preparing an oil emulsion.
Yet another object of the invention is to provide an oil emulsion which includes an oil; a base; the polymeric product; and water.
Preferred processes for preparing emulsions, emulsion compositions, processes for preparing dispersions, and dispersion compositions optionally include a conventional surfactant, preferably an anionic or non-ionic surfactant, in an amount up to about 10 percent by weight based on the total weight of solids.
Still another object of the invention is to provide a process for improving the viscosity profile of an aqueous pigment dispersion which includes adding the polymeric product of the continuous bulk polymerization and esterification process to an aqueous pigment dispersion.
A still further object of the invention is to provide an aqueous pigment dispersion with an improved viscosity profile that includes an aqueous pigment dispersion; and the polymeric product.
Yet another object of the invention is to provide a process for increasing the total solids concentration of an aqueous coating which includes adding the polymeric product of the continuous bulk polymerization and esterification process to an aqueous coating.
A still further object of the invention is to provide an aqueous coating having an increase in total solids which includes an aqueous coating; and the polymeric product.
Another object of the invention is to provide a process for stabilizing a compound in an aqueous medium which includes providing a resin melt of the polymeric product of the continuous bulk polymerization and esterification process in a reactor operating at or above atmospheric pressure; charging the reactor with a base and water; dispersing an oil or a wax into the resin melt; and charging additional water into the reactor.
In preferred processes and compositions, the base is ammonia, diethylaminoethanol, morpholine, sodium hydroxide, potassium hydroxide or mixtures of these.
Another object of the invention is to provide a stabilized compound prepared according to the above process.
Another object of the invention is to provide a polymeric surfactant which includes at least one ethylenically unsaturated acid-functional monomer which has been radically incorporated into the polymeric surfactant and at least one ester of the incorporated ethylenically unsaturated acid-functional monomer having an R alkyl group. The R group is a linear or branched chain alkyl moiety having greater than 11 carbon atoms, and the molar critical micelle concentration of the neutralized aqueous polymeric surfactant is less than 1.0xc3x9710xe2x88x922 moles/liter.
Another object of the invention is to provide a polymeric surfactant which includes at least one ethylenically unsaturated acid-functional monomer which has been radically incorporated into the polymeric surfactant and at least one ester of the incorporated ethylenically unsaturated acid-functional monomer having an R alkyl group. The R group is a linear or branched chain alkyl moiety having greater than 11 carbon atoms, and a 2 percent neutralized aqueous solution of the polymeric surfactant has a surface tension of less than 45 mN/m at 30xc2x0 C. and undergoes a decrease in surface tension of at least 5 mN/m as the temperature of the solution warms from 30xc2x0 C. to 50xc2x0 C.
In preferred embodiments, the surface area per molecule of the polymeric surfactant is less than 36 xc3x852. In other preferred embodiments, the molar critical micelle concentration of the polymeric surfactant is less than 8.2xc3x9710xe2x88x923 moles/liter, and in even more preferred embodiments, the molar critical micelle concentration is less than 1.0xc3x9710xe2x88x923 moles/liter. In still other preferred embodiments, the polymeric surfactant further includes at least one vinyl aromatic monomer incorporated into the polymeric surfactant, and in more preferred embodiments at least two vinyl aromatic monomers are incorporated into the polymeric surfactant.
Still another object of the invention is to provide a barrier coating that includes a polymeric product according to the invention, an emulsion polymer, and a paraffin wax emulsion. In preferred embodiments, the barrier coating has a water vapor transmission of less than 6, more preferably less than 3, grams per 100 square inches per 24 hours at 90 percent relative humidity and 37.8xc2x0 C.
Still further objects, features, and advantages of the invention will be apparent from the following detailed description when taken in conjunction with the drawings.